Sintered metals (e.g., cermets and cemented carbides) in which hard particles (hard phases) of carbides, carbonitrides, or the like are bonded with an iron group metal (binder phase), such as cobalt (Co) or nickel (Ni), have been used as substrates for cutting tools. In general, in a cermet, the main hard phase is composed of particles of a Ti compound, such as titanium carbide (TiC) or titanium carbonitride (TiCN). On the other hand, in a cemented carbide, the main hard phase is composed of tungsten carbide (WC) particles. Cutting tools including substrates composed of a cermet have the following advantages over cutting tools including substrates composed of a cemented carbide:
(1) excellent wear resistance,
(2) high surface quality in steel machining,
(3) capability of high-speed cutting,
(4) lightweight, and
(5) abundance and inexpensiveness of raw materials.
Techniques for performing a blast treatment on the surface of a substrate of a cutting tool composed of a sintered metal, thereby improving surface properties are described, for example, in Patent Literatures 1 to 4.
Patent Literatures 1 to 3 describe that, before a substrate of a drill or indexable insert is subjected to a coating treatment, by performing a blast treatment on the surface of the substrate, unwanted substances on the surface of the substrate are removed, thereby improving adhesion with the coating layer. Patent Literature 4 describes that, by performing a blast treatment on the surface of a rake face of an insert substrate composed of a cermet, ceramic particles, such as alumina particles, used as abrasive grains are embedded and scattered in the surface of the rake face so that welding resistance can be improved.